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Data Communications Cabling FAQ

This article is a collection of information sources, standards, implementation methods and definitions for data communications cabling.
Archive-name: LANs/cabling-faq
Posting-Frequency: monthly
Last-modified: 1995/03/05

         C A B L I N G    F A Q    

      Version 950305
     This is a Frequently Asked Questions (FAQ) document for the
     comp.dcom.cabling  newsgroup.   Topics  covered include the
     types of cables (fiber, coax,  copper,  unshielded  twisted
     pair-UTP, shielded twisted pair),  installation techniques,
     standards as well as fire and building safety codes.

     Prepared and maintained by Peter Macaulay (
     Constructive comments/updates are welcomed.

 0.1 Recent Updates

     The most recent changes are on the top of this list for easier
     identification of the new stuff (push down stack).  Format of
     the version is year, month, day.

     950305 - added approval, cable testing
     950124 - added bending radius specs, ISDN cabling
     950110 - added headers required for posting
     - expanded references with much help from Evan Gamblin

 0.2 Copyright

     Copyright (c) 1995 by Peter Macaulay, all rights reserved.

     This FAQ may be posted to any USENET newsgroup, on-line service,
     or BBS as long as it is posted in its entirety and includes this
     copyright statement.  

 0.3 Disclaimer

     This article is provided as is without any express or implied
     warranties.  While every effort has been taken to ensure the
     accuracy of the information contained in this article, the
     author and contributors assume no responsibility for errors
     or omissions, or for damages resulting from the use of the
     information contained herein.


 0.4 Acknowledgments (Bill Hughes) (Evan Gamblin)
     jlundgre@kn.PacBell.COM (John Lundgren) (Mike Barker)
     koeman@tc.fluke.COM (Henriecus Koeman)

 0.1 Recent Updates
 0.2 Copyright
 0.3 Disclaimer
 0.4 Acknowledgments
 1.0 Cable Types
 2.0 Cable Ratings
 3.0 National Electrical Code (NEC)
 4.0 Not Used (Blank)
 5.0 Specific Cable Classifications
 6.0 Cable Conductors
 7.0 Vendor Specific Suggestions
 8.0 Cabling Standards
 9.0 Standard EIA/TIA 568
10.0 Birds and Bees (Plugs vs. Jacks)
11.0 Standard Networking Configurations
12.0 Ethernet 10Base-T Cabling
13.0 Category Specifications
14.0 Sources for the EIA/TIA 568 Standards Documents
15.0 Cable Test Equipment
16.0 Cable Testers for Category 5
17.0 Typical Wiring Layout
18.0 How Far Away Should Cable be Installed from an EMI Source
19.0 What is the Minimum Bending Radius for a Cable?
20.0 Fiber Optic Cable
21.0 ISDN Cabling
22.0 Testing Unshielded Twisted Pair Cables
23.0 - 29.0 Not Used (Blank)
30.0 Sources of Additional Information


Subject: 1.0 Cable Types

     Communications Cable: primarily for telephone cable
     Class 2 Cable: signaling cable primarily for data communications
     Riser: vertical shaft used to route cable between floors
     Plenum: Heating, Ventilation, Air Conditioning (HVAC) air return
      area -- mostly drop ceilings. Also below raised floors
      (where the underfloor area is used for ventilation).


Subject: 2.0 Cable Ratings

     (Or What Are Those Codes Printed On My Cables?)
     In the Hollywood movie _Towering Infernio_ (starring O.J.Simpson)
     a fire spread from floor to floor using the building cables.  This
     will not happen again (we hope) since everyone is using fire rated
     cables!  These are important specifications if you are responsible
     for defining a cable installation.

     If interfloor penetrations are properly _firestopped_, the
     cables can burn, but the fire will not pass the firestopping.

     UL-910, FT-4 and FT-6 say nothing about the type or volume of toxic
     combustion products produced. All they cover is performance on a
     flamespread test.


     The US National Fire Protection Association (NFPA) revises the 
     National Electrical Code (NEC) every 3 years.  The NEC defines 
     classifications of cable as per UL tests.

     The Canadian Standards Association (CSA) defines Premise Communication
     Cord (PCC) standards for physical wire tests.  These are printed
     on the cable as CSA-PCC-FT6.

     FT4 = Flame Test 4 is described in CSA C22.2 0.3-1992
     FT6 = Flame Test 6 is described in NFPA 262-1985 and ULC S102.4
     Physical Wire Tests C22.2 214-M-1990.  These CSA documents can
     be ordered from the CSA.  See sources below.

     <<<Any comments on standards from other parts of the world?>>>


Subject: 3.0 National Electrical Code (NEC)

     1993 National Electrical Code

     Article 725, Class 2
   725-38(b)1      CL2X    Class 2 cable, limited use
   725-38(b)1      CL2     Class 2 cable
   725-38(b)2      CL2R    Class 2 riser cable
   725-38(b)3      CL2P    Class 2 plenum cable

     Article 800
   800-3(b)1       CMX     Communications cable limited use
   800-3(b)1       CM      Communications cable
   800-3(b)2       CMR     Communications riser cable
   800-3(b)3       CMP     Communications plenum cable

     OFNP (Optical Fiber Nonconductive Plenum)
     OFNR (Optical Fiber Nonconductive Riser)


Subject: 4.0 Not Used (Blank)


Subject: 5.0 Specific Cable Classifications

   CMS, CL2X (Restricted Cable) must be enclosed in conduit,
   up to 10 feet exposed; must pass UL 1581 VW-1 test

   CM, CL2 (General Purpose Cable) for use in areas other
   than risers or plenums; must pass UL 1581 vertical tray test

   CMR, CL2R (Riser Cable) for cable in vertical shafts;
   must pass UL test method 1666

   CMP, CL2P (Plenum Cable) for use in plenum areas (air ducts);
   must pass UL 910 test for smoke and flame spread


Subject: 6.0 Cable Conductors

     Cable conductor gauge is specified as AWG (American Wire Gauge).
     A higher number is a smaller diameter.  Telephone cable used indoors
     is typically 24 or 26 AWG, whereas household electrical wiring is
     typically 12 or 14 AWG.


Subject: 7.0 Vendor Specific Suggestions

      AMP NETCONNECT Open Cabling System
      HP SiteWire
      AT&T PDS
      DEC MMJ
      IBM STP (Type 1, Type 2, etc)
      Northern Telcom IBDN


Subject: 8.0 Cabling Standards

     American National Standards Institute (ANSI)
     Electronic Industry Association (EIA)
     Telecommunications Industry Association (TIA)

     Current specification is the ANSI/EIA/TIA-568-1991 Standard
     _Commercial Building Telecommunications Wiring Standard_ and
     two Tech Sys Bulletins:

     _Additional Cable Specifications for Unshielded Twisted-Pair Cables_
     EIA/TIA Tech Sys Bulletin TSB-36, Nov 1991
     [Transmission Characteristics of Category 3-5 UTP cables]

     _Additional Transmission Specifications for UTP Connecting Hardware_
     EIA/TIA Tech Sys Bulletin TSB-40A, Dec 1993
     (Performance of Connectors and Patch Panels Above 20 MHz)

     Extended Specifications for 150-ohm STP Cables and Data
     Connectors - EIA/TIA Tech Sys Bulletin TSB-53, 1992 [Type 1A cable]

     EIA-570: Residential and Light Commercial Telecommunications
     Wiring Standard - EIA/TIA, 1991

     EIA-606: Telecommunications Administration Standard for Commercial
     Buildings - EIA/TIA (was PN-2290)

     EIA-607: - Commercial Building Grounding and Bonding Requirements
     for Telecommunications - EIA/TIA

     EIA/TIA PN-2840 - [draft for the EIA-568-A standard, incorporating
     TSB-36 and -40A, expected in early 1995]

     EIA/TIA PN-2840A - [draft for next version of the EIA-568-A standard]

     American National Standards Institute (ANSI)/
     National Fire Protection Assoc. (NFPA):
    70     National Electrical Code (1993)
    78     Lightning Protection Code

     Canadian Standards Association (CSA):
    C22.1-1994   Canadian Electrical Code, Part 1

     CAN/CSA-T527: Bonding and Grounding for Telecommunications
     in Commercial Buildings - Canadian Standards Assoc.
     [harmonized with EIA-607]

     CAN/CSA-T528: Telecommunications Administration Standards for
     Commercial Buildings - CSA, Jan 1993 [harmonized with EIA-606]

     CAN/CSA-T529-M91: Design Guidelines for Telecommunications Wiring
     System in Commercial Buildings, - CSA [harmonized with EIA-568]

     CAN/CSA-T530-M90: Building Facilities, Design Guidelines for
     Telecommunications - CSA, 1990  [harmonized with EIA-569]

     ISO/IEC 11801: [international equivalent of EIA-568 and CSA T-529,
     includes 120 ohm Screened Twisted Pair cable]

     IEC 603-7, Part 7 - [Modular connector physical dimensions, mechanical
     and electrical characteristics. Level A: 750 mating cycles min;
     B: 2,500 min; C: 10,000 min.]

     ISO 8877: Information Processing Systems - Interface Connector and
     Contact Assignment for ISDN Basic access interface located at
     reference points S and T - International Organization for
     Standardization [same pin/pair assignments for 8-line modular
     connector as EIA T-568A]

     National Electrical Safety Code Handbook (NESC):
     Institute of Electrical and Electronic Engineers (IEEE)/
     American National Standards Institute (ANSI):
      C2-1993      National Electrical Safety Code
     ISBN 1-55937-210-9 (order # SH15172)
     [In USA, governs the area between the property line and the
     building entrance]

     National Research Council of Canada, Institute for Research in
     Construction (NRC-IRC):
    National Building Code of Canada (1990) - order NRCC 30619
    Supplement to the National Building Code of Canada (1990)
    - order NRCC 30629
    National Fire Code of Canada (1990) - order NRCC 30621

     A Guide to Premises Distribution
     - NCR/AT&T order #555-400-021, Apr 1988

     Building Network Design - Bell Canada, 1992

     The Corporate Cabling Guide - M. McElroy,
     Artech House, ISBN 0-89006-663-9, Dec 1992

     Telecommunications Distribution Methods Manual (1050 pages)
     - Building Industries Consulting Service International (BICSI), 1994

     Universal Transport System Design Guide, Release II
     - Siecor Corp, 1991 [fiber-optic cable plant]

     Requirements Beyond Jacks and Cable: an Installation Guide
     - Leviton Telecom, Second edition, T15-00004-003, Jan 1994

     SiteWire Twisted-pair Installation Guide
     - Hewlett-Packard,  p/n 5959-2208, Jan 1988

     SiteWire Planning Guide - Hewlett-Packard, p/n 5959-2201,
     Sept 1989

     Tech Ref Guide for Workgroup LANs
     - Hewlett-Packard, p/n 5091-0663E, Apr 1991

     Tech Ref Guide for Site LANs and MultiSite LANs
     - Hewlett-Packard, p/n 5091-0666E, Apr 1991

     Understanding Fiber Optics - J. Hecht
     Howard Sams & Co., ISBN 0-672-27066-8, 1988

     Optical Fiber Communications, I & II - S. Miller
     Academic Press, ISBN 0-12-497350-7 & -5

     Optical Fiber Splices and Connectors: Theory & Methods -
     C. M. Miller, Marcel Dekker, 1986

     Principles of Optical Fiber Measurements - D. Marcuse
     Academic Press, ISBN 0-12-470-980-X, 1981

     Single-Mode Fibers: Fundamentals - E. G. Neumann
     Springer-Verlag, ISBN 0-387-18745-6, 1988

     CATV Cable Construction Manual, 3rd edition - Comm/Scope Inc., 1980
     [Outside Plant tools and procedures: trenching, boring, installing
     aerial and buried cable]

     Marking Guide: Wire and Cable - Underwriters Labs, 1993
     [How to interpret UL cable jacket markings]


Subject: 9.0 Standard EIA/TIA 568

     The ANSI/EIA/TIA-568-1991 Standard _Commercial Building
     Telecommunications Wiring Standard_ defines pinouts;

     9.1 Standard EIA/TIA T568A
  (also called ISDN, previously called EIA)

        Pin  Wire Color
        ===  ==========
         /--T3  1   White/Green
   Pair3 \--R3  2   Green
        /----------T2  3   White/Orange
       /         /-R1  4   Blue
 pair2 \   pair1 \-T1  5   White/Blue
        \----------R2  6   Orange
         /--T4  7   White/Brown
   pair4 \--R4  8   Brown

     9.2 Standard EIA/TIA T568B
  (also called AT&T specification, previously called 258A)

         /--T2  1   White/Orange
   pair2 \--R2  2   Orange
        /----------T3  3   White/Green
       /         /-R1  4   Blue
 pair3 \   pair1 \-T1  5   White/Blue
        \----------R3  6   Green
         /--T4  7   White/Brown
   pair4 \--R4  8   Brown

     9.3 USOC (Universal Service Order Code)

   8-pins    6-pins
         |  |
     /-------------T4  1     White/Brown
    /    /---------T3  2  1  White/Green
   /    /    /-----T2  3  2  White/Orange
  /    /    /    /-R1  4  3  Blue
      pr4\ pr3\ pr2\ pr1\-T1  5  4  White/Blue
   \    \    \-----R2  6  5  Orange
    \    \---------R3  7  6  Green
     \-------------R4  8     Brown


Subject: 10.0 Birds and Bees (Plugs vs. Jacks)

     The EIA/TIA specifies an RJ-45 (ISO 8877) connector for Unshielded
     Twisted Pair (UTP) cable.  The plug is the male component crimped
     on the end of the cable while the jack is the female component in
     a wall plate or patch panel, etc.  Here is the pin numbering to
     answer the question, where is pin one?

  Plug                          Jack
  (Looking at connector          (Looking at cavity
   end with the cable             in the wall)
   running away from you)

      ---------- /                   ----------
     | 87654321 |                   | 12345678 |
     |__      __|/                  |/_      /_|
        |____|                         |/___|


Subject: 11.0 Standard Networking Configurations

     With reference to T568B above;
      ATM 155Mbps uses pairs 2 and 4 (pins 1-2, 7-8)
      Ethernet 10Base-T uses pairs 2 and 3 (pins 1-2, 3-6)
      Ethernet 100Base-T4 uses pairs 2 and 3 (4T+) (pins 1-2, 3-6)
      Ethernet 100Base-T8 uses pairs 1,2,3 and 4 (pins 4-5, 1-2, 3-6, 7-8)
      Token-Ring uses pairs 1 and 3 (pins 4-5, 3-6)
      TP-PMD uses pairs 2 and 4 (pins 1-2, 7-8)
      100VG-AnyLAN uses pairs 1,2,3 and 4 (pins 4-5, 1-2, 3-6, 7-8)


Subject: 12.0 Ethernet 10Base-T Cabling

     12.1 Ethernet 10Base-T Straight Thru patch cord (T568B colors);

         RJ45 Plug        RJ45 Plug
         =========        =========
         /--T2  1  ... White/Orange .... 1  TxData +
   pair2 \--R2  2  ... Orange .......... 2  TxData -
        /----------T3  3  ... White/Green ..... 3  RecvData +
       /           R1  4      Blue              4
       \  pair3    T1  5      White/Blue        5
        \----------R3  6  ... Green ........... 6  RecvData -
     T4  7      White/Brown       7
     R4  8      Brown             8

     12.2 Ethernet 10Base-T Crossover patch cord;
    This cable can be used to cascade hubs, or for connecting
    two Ethernet stations back-to-back without a hub (ideal for
    two station Doom!)  Note pin numbering in item 10.0 above.

     RJ45 Plug  1 Tx+ -------------- Rx+ 3  RJ45 Plug
         2 Tx- -------------- Rx- 6
         3 Rx+ -------------- Tx+ 1
         6 Rx- -------------- Tx- 2

     12.3 Ethernet 10Base-T to USOC Crossover patch cord;

      RJ45 8-pin Plug  1 ---White/Orange--- 2  USOC 6-pin Plug
    ^           2 ------Orange------ 5       ^
         3 ---White/Green---- 1
         6 ------Green------- 6

     12.4 Crossover Implementation
   A simple way to make a crossover patch cable is to take a 
   dual-jack surface mount box and make the crossover between 
   the two jacks. This allows using standard patch cables, and 
   avoids the nuisance of having a crossover cable find its way 
   into use in place of a regular patch cable.

     12.5 Stranded Patch Cables
   The color code used in stranded patch cables is different from 
   solid-conductor cables. For NorTel Digital Patch Cable (DPC), 
   the coding is;
   Pair 1: Green & Red
   Pair 2: Yellow & Black
   Pair 3: Blue & Orange
   Pair 4: Brown & Gray


Subject: 13.0 Category Specifications

     EIA/TIA Category Specification provide for the following cable
     transmission speeds with specifications (Note prior to Jan94
     UL and Anixter developed a LEVEL system which has been dropped
     or harmonized with the CATEGORY system);

 Category 1 = No performance criteria
 Category 2 = Rated to 1 MHz (used for telephone wiring)
 Category 3 = Rated to 16 MHz (used for Ethernet 10Base-T)
 Category 4 = Rated to 20 MHz (used for Token-Ring, 10Base-T)
 Category 5 = Rated to 100 MHz (used for 100Base-T, 10Base-T)

     UL LAN Cable Certification Program - Underwriters Laboratories
     publication 200-120 30M/3/92, 1992 [characteristics of Cat 3-5 UTP]


Subject: 14.0 Sources for the EIA/TIA 568 Standards Documents

     EIA Standards Sales Office -or-
     Global Engineering Documents (east or west coast offices)
     (See addresses in sources below)


Subject: 15.0 Cable Test Equipment

     15.1 DVM
     DVM = Digital Volt Meter (measures volts)
     15.2 DMM
     DMM = Digital Multi Meter (measures volts, ohm, capacitance,
    and some measure frequency)

     15.3 TDR
     TDR = Time Domain Reflectometer (measures cable lengths, 
    locates impedance mismatches).

     15.4 Tone Generator
     Tone Generator and Inductive Amplifier = Used to trace cable pairs,
     follow cables hidden in walls or ceiling. The tone generator will
     typically put a 2 kHz audio tone on the cable under test, the 
     inductive amp detects and plays this through a built-in speaker.
     15.5 Wirmap Tester
     Wiremap tester: checks a cable for open or short circuits, reversed 
     pairs, crossed pairs and split pairs.

     A least-cost wiremap type tester that detects split pairs correctly
     (using a NEXT test) is the Fluke 610, at $400.  MOD-TAP and UNICOM
     make a similar device.

     15.6 Noise Tester
     Noise tests, 10Base-T: the standard sets limits for how often
     noise events can occur, and their size, in several frequency ranges.
     Various handheld cable testers are able to perform these tests.

     15.7 Butt-in
     Butt-in set: a telephone handset that when placed in series with a
     battery (such as the one in a tone generator), allows voice communication
     over a copper cable pair. Can be used for temporary phone service in a
     wiring closet.

     15.7 Fiber Testing
     See section 20.7 for fiber optic test equipment.


Subject: 16.0 Cable Testers for Category 5

    _LANcat V_     by Datacom Technologies
        Everett, WA
        Tel: 800/468-5557

    _DSP100_       by Fluke Corporation
        P.O. Box 9090
        Everett, WA 98206-9090
        Tel: 206/356-5400  800/44-FLUKE

    _PentaScanner_ by Microtest, Inc
        4747 North 22nd St,
        Phoenix, AZ  85016
        Tel: 602/952-6400  800/526-9675

    _WireScope100_ by Scope Communications, Inc
        100 Otis St,
        Northboro, MA  01532
        Tel: 508/393-1236

    _LANTech PRO_  by Wavetek, Inc
        9145 Balboa Ave
        San Diego, CA  92123
        Tel: 619/279-2200  800/854-2708

    At present some vendors are calling their instruments _CAT 5
    conformance_ testing devices. Be aware that there is an on-going
    standards process to define field testing of CAT 5 cables.  These
    standards or guidelines (currently called PN-3287) will not be
    complete until the June 1995 timeframe.

    The TIA TSB number will be TSB-67 when PN-3287 is approved.

    The standard is expected to define two accuracy levels of test 
    equipment, and provide minimum performance standards for each. 
    Current test equipment is likely to fall in the lower level. The 
    higher class (_Accuracy Level II_) is intended for subsequent 
    generations of test equipment capable of performing the 
    increasingly numerous and stringent tests now being developed.


Subject: 17.0 Typical Wiring Layout

    17.1 Wiring Layout

    ......Wiring Closet..............                ....User Work Area....

    Where ...
   HUB = concentrator
   PANEL = RJ-45 Modular Patch Panel

   BLOCK = Telco Splice Block (Typically 25-pair)

   Crossconnect: NorTel BIX1A, AT&T 110 and similar crossconnect 
   blocks accommodate 4-pair, 25-pair or larger cables on the 
   same mount. The same type of mount can be used for the voice 
   field as well as data.
   Telephone-only (66) blocks are seldom used except for 
   low-speed data circuits such as are used for IBM 3270 terminals. 
   The newer types of crossconnect mentioned above cost about the 
   same and accommodates growth much better. (The standard AT&T 110 
   and its BIX equivalent are rated at Cat 5).

   LOBE CABLE = Cable run from user wall plate to wiring closet
   WALL = User area wall face plate
   STATION = User workstation network adapter
   =====>  = RJ-45 connector
   =====+  = Punch down termination (also called an insulation-
      displacement/displacing connector, or IDC).

     17.2 Crossconnect Field Colors
     The color of label used on a crossconnect field identifies the
     field's function. The cabling administration standard (CSA T-528
     & EIA-606) lists the colors and functions as:

   Blue  Horizontal voice cables
   Brown  Interbuilding backbone
   Gray  Second-level backbone
   Green  Network connections & auxiliary circuits
   Orange Demarcation point, telephone cable from Central Office
   Purple  First-level backbone
   Red  Key-type telephone systems
   Silver or
   White  Horizontal data cables, computer & PBX equipment
   Yellow Auxiliary, maintenance & security alarms


Subject: 18.0 How Far Away Should Cable be Installed from an EMI Source

     Northern Telecom IBDN User Manual contains an Appendix D titled 
     _UTP Separation Guidelines From EMI Sources_. The values are the
     same as the cabling pathways standard, EIA-569, table 4.8-5.

      Minimum Separation Distance
           from Power Source at 480V or less
     CONDITION                           <2kVA      2-5kVA       >5kVA
     Unshielded power lines or
     electrical equipment in proximity
     to open or non-metal pathways         5 in.     12 in.     24 in.
      (12.7 cm)  (30.5 cm)  (61 cm)
     Unshielded power lines or
     electrical equipment in proximity
     to grounded metal conduit pathway    2.5 in.     6 in.     12 in.
      (6.4 cm)  (15.2 cm)   (30.5 cm)
     Power lines enclosed in a grounded
     metal conduit (or equivalent
     shielding) in proximity
     to grounded metal conduit pathway      -         6 in.     12 in.
         -      (15.2 cm)   (30.5 cm)

     Transformers & electric motors       <------- 40-in (1.02 m) ----->

     Fluorescent lighting                 <------- 12-in (30.5 cm) ---->

     Source: Integrated Building Distribution Network (IBDN) User Manual
     - Northern Telecom, doc # IBDN-UM-9105, 1991.

     The EIA/TIA working group revising the EIA-569 standard is using the
     results of field and lab tests to update the recommendations. The 
     target date for completion is Dec 1995.


Subject: 19.0 What is the Minimum Bending Radius for a Cable?

     According to EIA SP-2840A (a draft version of EIA-568-x) the minimum
     bend radius for UTP is 4 x cable outside diameter, about one inch.
     For multipair cables the minimum bending radius is 10 x outside 

     SP-2840A gives minimum bend radii for Type 1A Shielded Twisted Pair
     (100 Mb/s STP) of 7.5 cm (3-in) for non-plenum cable, 15 cm (6-in)
     for the stiffer plenum-rated kind.

     For fiber optic cables not in tension, the minimum bend radius is 10 x
     diameter; cables loaded in tension may not be bent at less than 20 x
     diameter. SP-2840A states that no f/o cable will be bent on a radius
     less than 3.0 cm (1.18-in).

     The ISO DIS 11801 standard, Section 7.1 General specs for 100 ohm 
     and 120 ohm balanced cable lists three different minimum bend radii. 
     Minimum for pulling during installation is 8x cable diameter, min 
     installed radius is 6x for riser cable, 4x for horizontal.

     For fiber optic cables not in tension, the minimum bend radius is 
     10 x diameter; cables loaded in tension may not be bent at less 
     than 20 x diameter. SP-2840A states that no f/o cable will be 
     bent on a radius less than 3.0 cm (1.18-in).

     Some manufacturers recommendations differ from the above, so it is
     worth checking the spec sheet for the cable you plan to use.


Subject: 20.0 Fiber Optic Cable

     20.1 Multimode (MM) Fiber
     Step index or graded index fiber. In North America the most common 
     size is 62.5/125; in Europe, 50/125 is often used.  These numbers 
     represent the diameter of the core (62.5) and diameter of the 
     cladding (125) in microns.  Multimode fiber is typically used in 
     applications such as local area networks, at distances less than 2 km.

     20.2 Single Mode (SM) Fiber
     Single mode fiber has a very small core.  Typical values are
     5-10 microns.  Single mode fiber has a much higher capacity and
     allows longer distances than multimode fiber.  Typically used
     for wide area networks such as telephone company switch to switch
     connections and cable TV (CATV).

     20.3 Loose Buffer
     The fiber is contained in a plastic tube for protection.
     To give better waterproofing protection to the fiber, the space 
     between the tubes is sometimes gel-filled. Typical applications 
     are outside installations. One drawback of loose buffer construction 
     is a larger bending radius. Gel-filled cable requires the installer 
     to spend time cleaning and drying the individual cables, and 
     cleaning up the site afterwards.

     20.4 Tight Buffer
     Buffer layers of plastic and yarn material are applied over the fiber.
     Results in a smaller cable diameter with a smaller bending radius.
     Typical applications are patch cords and local area network connections.
     At least one mfr. produces this type of cable for inside/outside use.

     20.5 Ribbon Cable
     Typically 12 coated fibers are bonded together to form a
     ribbon.  There are higher density ribbons (x100) which have
     the advantage of being mass-terminated into array connectors.
     A disadvantage is that they are often harder, and require special 
     tools to terminate and splice.

     20.6 Fiber Connectors
     There are a lot of different types of connectors, but the ones 
     commonly found in LAN/MAN/WAN installations are:

     FSD - Fixed Shroud Device, such as the FDDI MIC dual-fiber connector.
     SC  - A push-pull connector. The international standard.
    The SC connectors are recommended in SP-2840A.  The SC
    connector has the advantage (over ST) of being duplexed
    into a single connector clip with both transmit/receive fibers.
     SMA - Threaded connector, not much used anymore because of losses
    that change with each disconnection and reconnection.
     ST  - Keyed, bayonet-style connector, very commonly used.

     20.7 Fiber Optic Test Equipment
     Continuity tester: used to identify a fiber, and detect a break. 
     One type resembles a f/o connector attached to a flashlight.
     Fault locator:  used to determine exact location of a break. 
     Works by shining a very bright visible light into the strand. 
     At the break, this light is visible through the cable jacket.
     Tone Generator and Tracer: used to identify a cable midspan or 
     to locate a strand at its far end. Similar in purpose to the
     tone testers used on copper cable. The tone generator imposes 
     a steady or warbling audio tone on light passing down the cable. 
     The tracer detects and recovers the tone from light lost through 
     the cable jacket as a result of bending the cable slightly.
     Optical Source and Power Meter: used to measure the end-to-end 
     loss through a f/o strand, or system of cable, connectors and 
     patch cables. Measurements are more accurate than an OTDR.
     Optical Time Domain Reflectometer (OTDR): used to measure the length 
     of a cable, and detect any flaws in it. Can also be used to measure 
     end-to-end loss, although less accurately than a power meter.
     Fiber Talk set: allows using a pair of f/o strands as a telephone line.

     Fiber Optic Testing, standards: see EIA-455-171 (FOTP-171), EIA 526-14.


Subject: 21.0 ISDN Cabling

     21.1 ISDN U-loop
     ISDN Basic Rate Interface (BRI) is provided by a carrier from
     a central office (CO) switch to the customer premise with a
     two wire U-loop RJ-45 connector on the center pins 4-5.

         RJ45 Plug
         1  N/C
         2  N/C
         3  N/C
         4  U-loop network connection
         5  U-loop network connection
         6  N/C
         7  N/C
         8  N/C

     21.2 ISDN Network Termination (NT)
     The Network Termination is a Power Supply and NT1.  In North
     America this functionality can be provided in the terminal
     equipment (i.e. ISDN digital modem) or separate as follows;
  ________              ________
        | Power  |            |        |========== TE
      =========| Supply |============|  NT1   |
 U-loop |________|   U+PS2    |________|========  S/T bus
 2-wire              4-wire                       4-wire
         RJ45 Plug for U+PS2
         1  N/C
         2  N/C
         3  N/C
         4  U-loop network connection
         5  U-loop network connection
         6  N/C
         7  -48 VDC 
         8  -48 VDC Return

     The ISDN cables can be silver satin patch cables (the kind that
     make 10Base-T Ethernet installers cringe).  The S/T bus can also
     be silver satin but most installers use CAT 3 or CAT 5 with one
     drop per terminal equipment.  It is true that only 4-wires are
     needed on the S/T bus but see below for optional power needs.

     21.3 ISDN S/T Bus (Point-to-Point)
     One logical terminal is on the S/T bus which can be 1km long.

     21.4 ISDN S/T Bus (Short Passive)
     Up to eight terminals on the S/T bus which can be within 100 to

     21.5 ISDN S/T Bus (Extended Passive)
     Up to eight terminals on the S/T bus which can be up to 500m.

     21.6 ISDN S/T Bus (NT1 Star)
     Up to eight terminals on the S/T bus which are wired from a
     central NT1 and can be up to 1km in length each.

     21.7 ISDN S/T Bus Pinout
     The S/T bus connects the NT1 with the terminal equipment.  See
     section 10.0 for plug identification and pin numbering.  Note,
     if power is not required an RJ11 (6-pin) plug could be used.
     Some NT1 devices have a switch to turn off power if it is not
     required by the terminal equipment.  For safety reasons the
     power should not be put on the S/T bus if it is not required.
     Typically, ISDN PC cards do not require power from the S/T bus,
     but ISDN telephones do require power from the S/T bus.  Check
     your vendor equipment specifications carefully.

         RJ45 Plug for ISDN S/T bus  
         1  N/C
         2  N/C
         3  White/Green .....  Receive +
         4  Blue ............  Transmit+
         5  White/Blue ......  Transmit-
         6  Green ...........  Receive -
         7  White/Brown .....  -48VDC (option)     
         8  Brown ...........  -48VDC Return (option)

     21.8 ISDN Cabling Guidelines
     The North American ISDN Users Forum (NIUF) has produced a document
     titled _ISDN Wiring and Powering Guidelines_ NIUF #433-94 which 
     describes residence and small business ISDN cabling.  See section
     30.0 for the NIUF document ordering address.


Subject: 22.0 Testing Unshielded Twisted Pair Cables

     22.1 Testing UTP Introduction
     Many of the problems encountered in UTP cable plants are a result 
     of miswired patch cables, jacks and crossconnects.

     Horizontal and riser distribution cables and patch cables are wired
     straight through end-to-end -- pin 1 at one end should be connected 
     to pin 1 at the other. (Crossover patch cables are an exception, as
     described later). Normally, jacks and crossconnects are designed so
     that the installer always punches down the cable pairs in a standard
     order, from left to right: pair 1 (Blue), pair 2 (Orange), pair 3
     (Green) and pair 4 (Brown). The white striped lead is usually punched
     down first, followed by the solid color. The jack's internal wiring
     connects each pair to the correct pins, according to the assignment
     scheme for which the jack is designed: EIA-568A, 568B, USOC or
     whatever. (One source of problems is an installation in which USOC
     jacks are mixed with EIA-568A or 568B. Everything appears to be
     punched down correctly, but some cables work and others do not).

     22.2 Wiremap Tests
     Wiremap tests will check all lines in the cable for all of the
     following errors:

       Open:          Lack of continuity between pins at both ends of
        the cable.
       Short:         Two or more lines short-circuited together.
       Crossed pair:  A pair is connected to different pins at each 
        end (example: pair 1 is connected to pins 4&5 
        at one end, and pins 1&2 at the other).
       Reversed pair: The two lines in a pair are connected to opposite
        pins at each end of the cable (example: the line 
        on pin 1 is connected to pin 2 at the other end, 
        the line on pin 2 is connected to line 1). Also 
        called a polarity reversal or tip-and-ring reversal.
       Split pair:    One line from each of two pairs is connected as if 
        it were a pair (example: the Blue and White-Orange 
        lines are connected to pins 4&5, White-Blue and 
        Orange to pins 3&6). The result is excessive Near 
        End Crosstalk (NEXT), which wastes 10Base-T 
        bandwidth and usually prevents 16 Mb/s token-ring 
        from working at all.    

     22.3 Length Tests
     Checking cable length is usually done using a time domain 
     reflectometer (TDR), which transmits a pulse down the cable, and 
     measures the elapsed time until it receives a reflection from the 
     far end of the cable. Each type of cable transmits signals at 
     something less than the speed of light.  This factor is called the 
     nominal velocity of propagation (NVP), expressed as a decimal 
     fraction of the speed of light. (UTP has an NVP of approximately 
     0.59-0.65). From the elapsed time and the NVP, the TDR calculates 
     the cable's length. A TDR may be a special-purpose unit such as 
     the Tektronix 1503, or may be built into a handheld cable tester.

     22.4 Testing for Impulse Noise
     The 10Base-T standard defines limits for the voltage and number of
     occurrences/minute of impulse noise occurring in several frequency
     ranges. Many of the handheld cable testers include the capability
     to test for this.

     22.5 Near-End Crosstalk (NEXT)
     What's NEXT, you ask? Imagine yourself speaking into a telephone.
     Normally, as you speak you can hear the person on the other end
     and also hear yourself through the handset. Imagine how it would
     sound if your voice was amplified so it was louder than the other
     person's. Each time you spoke you'd be deaf to anything coming from
     the other end. A cable with inadequate immunity to NEXT couples so
     much of the signal being transmitted back onto the receive pair
     (or pairs) that incoming signals are unintelligible.

     Cable and connecting hardware installed using poor practices can have
     their NEXT performance reduced by as much as a whole Category.

     22.6 Attenuation
     A signal traveling on a cable becomes weaker the further it travels.
     Each interconnection also reduces its strength. At some point the
     signal becomes too weak for the network hardware to interpret reliably.
     Particularly at higher frequencies (10MHz and up) UTP cable attenuates
     signals much sooner than does co-axial or shielded twisted pair cable.
     Knowing the attenuation (and NEXT) of a link allows you to determine
     whether it will function for a particular access method, and how much
     margin is available to accommodate increased losses due to temperature
     changes, aging, etc.
     Forthcoming updates to cabling standards call for a number of new
     tests which will add to this list.


Subject: 23.0 - 29.0 Not Used (Blank)

     These sections are blank for future topics.


Subject: 30.0 Sources of Additional Information

     Addr: Harrisburg, PA  17105-3608
     Tel:  1-800-722-1111
    1-800-245-4356 (Faxback service, USA)
    (905) 470-4425 Canada
    (617) 270-3774 (Faxback service, Canada)

    (An international cable products distributor)
    see _Anixter 199x Cabling Systems Catalog_
     Addr: Anixter, Inc
    4711 Golf Road
    Skokie, IL  60076
     Tel:  (708) 677-2600
    1-800-323-8167 USA
    1-800-361-0250 Canada
    32-3-457-3570 Europe
    44-81-561-8118 UK
    65-756-7011 Singapore

     Addr: American National Standards Institute
    11 W. 42nd St, 13th floor
    New York, NY 10036
     Tel:  (212) 642-4900

  AT&T Canada:
     Addr: Network Cables Div
    1255 route Transcanadienne
    Dorval, QC H3P 2V4
     Tel:  (514) 421-8213
     Fax:  (514) 421-8224

  AT&T documents:
     Addr: AT&T Customer Information Center
    Order Entry
    2855 N. Franklin Road
    Indianapolis, IN 46219 USA
     Tel:  (800) 432-6600 (USA)
    (800) 255-1242 (CDN)
    (317) 352-8557 (International)
     Fax:  (317) 352-8484

  Belden Wire & Cable:
     Addr: POB 1980
    Richmond, IN 47375
     Tel:  (317) 983-5200

  Bell Canada:
     Addr: Bell Canada
    Building Network Design
    Floor 2, 2 Fieldway Road
    Etobicoke, Ontario
    Canada M8Z 3L2
     Tel:  (416) 234-4223
     Fax:  (416) 236-3033

  Bell Communications Research (Bellcore):
     Addr: Customer Service
    60 New England Ave
    Piscataway, NJ 08854
     Tel:  (800) 521-2673
     Fax:  (908) 336-2559

  Berk-Tek: (copper & f/o cable)
     Addr: 312 White Oak Rd
    New Holland, PA 17557
     Tel:  (717) 354-6200, 1-800-BERK-TEK
     Fax:  (717) 354-7944

  BICSI:   A telecommunications cabling professional association.
    Offers education, and administers the RCDD (Registered
    Communications Distribution Designer) certification.
     Addr: Building Industries Consulting Service International
    10500 University Center Drive, Ste 100
    Tampa, FL 33612-6415
     Tel:  (813) 979-1991, 1-800-BICSI-05
     Fax:  (813) 971-4311

    Black Box Catalog: The Source for Connectivity (r)
     Addr: Black Box Inc
    P.O. Box 12800
    Pittsburgh, PA  15241
     Tel:  1-800-552-6816 USA
    (412) 746-5500 Tech Support USA
    (416) 736-8013 Tech Support Canada

     Addr: Canadian Automated Buildings Association
    M-20, 1200 Montreal Rd
    Ottawa, ON K1A 0R6
     Tel:  (613) 990-7407
     Fax:  (613) 954-5984

  CableTalk: (racks & physical cable management)
     Addr: 18 Chelsea Lane
    Brampton, ON L6T 3Y4
     Tel:  (800) 267-7282
    (905) 791-9123
     Fax:  (905) 791-9126

  Cabling Business:
     Addr: Cabling Business Magazine
    12035 Shiloh Road, Ste 350
    Dallas, TX 75228
     Tel:  (214) 328-1717
     Fax:  (214) 319-6077

  Cabling Installation & Maintenance Magazine:
     Addr: Cabling Installation & Maintenance
    Editorial Offices
    One Technology Park Dr
    POB 992
    Westford, MA 01886
     Tel:  (508) 692-0700
     Tel:  (918) 832-9349
     Fax:  (918) 832-9295

  CCITT:   See ITU

  Comm/Scope Inc.
     Addr: POB 1729,
    Hickory, NC 28603
     Tel:  (800) 982-1708 (USA)
    (704) 324-2200
     Fax:  (704) 328-3400

     Addr: Corning Optical Fiber Information Center
     Guidelines - publication/newsletter on fiber technology
     FiberFax-on-Demand: ???

     Addr: Canadian Standards Association
    178 Rexdale Blvd
     Rexdale, Ont
     Canada M9W 1R3
     Tel:  (416) 747-4000, Documents Orders: (416) 747-4044
     Fax:  (416) 747-2475

     Addr: EIA Standards Sales Office
    2001 Pennsylvania Ave., N.W.
    Washington, DC  20006
     Tel:  (202) 457-4966

     Addr: Global Engineering Documents
    1990 M Street W, Suite 400
    Washington, DC 20036
     Tel:  (800) 854-7179 (CDN/USA)
    (202) 429-2860 (International)
    (714) 261-1455 (International)
     Fax:  (317) 352-8484

    Global Engineering Documents (West Coast)
    2805 McGaw Ave.
    Irvine, CA  92714

    (An international cable products distributor)
     Tel:  (519) 576-4050 in Ontario
     Fax:  (519) 576-2402

     Addr: Hubbell Premise Wiring Inc.
    14 Lords Hill Rd
    Stonington, CT 06378
     Tel:  (203) 535-8326
     Fax:  (203) 535-8328

     Addr: International Electrotechnical Commission
    rue de Varembre, Case Postale 131,3
    Geneva 20, Switzerland

     Addr: International Organization for Standardization
    1, rue de Varembre, Case Postale 56
    Geneva 20, Switzerland
     Tel:  +41 22 34 12 40

    (Previously called CCITT)
     Addr: International Telephone Union
    Place des Nations
    Geneva 20, Switzerland

    (Cable and Equipment Suplier)
     Addr: Mod-Tap
    285 Ayer Rd, P.O. Box 706
    Harvard, MA  01451
     Tel:  (508) 772-5630
     Fax:  (508) 772-2011

  NFPA (US National Electrical Code (NEC) and other docs):
     Addr: National Fire Protection Association
    One Battery March Park, P.O. Box 9146
    Quincy, MA 02269-9959
     Tel:  (800) 344-3555
     Fax:  (617) 984-7057

     Addr: U.S. Dept. of Commerce
    National Institute of Standards and Technology
    Technology Building 225
    Gaithersburg, MD 20899
     Addr: North American ISDN Users Forum
    NIUF Secretariat
    National Institute of Standards and Technology
    Bldg 223, Room B364
    Gaithersburg, MD 20899
     Tel:  (301) 975-2937
     Fax:  (301) 926-9675

  Northern Telecom (cable and physical network products):
     Addr: Business Networks Div.
    105 Boulevard Laurentien
    St. Laurent, QC H4N 2M3
     Tel:  (514) 744-8693, 1-800-262-9334
     Fax:  (514) 744-8644

     Addr: U.S. Dept. of Commerce
    National Technical Information Service
    5285 Port Royal Rd
    Springfield, VA 22161
     Tel:  (703) 487-4650
    (800) 336-4700 (rush orders)
     Fax:  (703) 321-8547

  NRC of Canada:
     Addr: Client Services
    Institute for Research in Construction
    National Research Council of Canada
    Ottawa, ON K1A 0R6
     Tel:  (613) 993-2463
     Fax:  (613) 952-7673

     Addr: 595 Greenhaven Rd
    Pawcatuck, CT 06379
      Tel: (203) 599-1760
      Fax: (203) 599-1774

  RCDD:    See BICSI

  Saunders Telecom: (racks, tray and accessories)
     Addr: 8520 Wellsford Place
    Santa Fe Springs, CA
     Tel:  (800) 927-3595
     Fax:  (310) 698-6510

     Addr: Standards Council of Canada
    1200-45 O/Connor St
    Ottawa, Ont Canada K1P 6N7
     Tel:  (613) 238-3222
     Fax:  (613) 995-4564

     Addr: 489 Siecor Park, POB 489
    Hickory, NC 28603-0489
     Tel:  (704) 327-5000
     Fax:  (704) 327-5973

    The Siemon Co (Cabling System Supplier)
     Addr: 76 Westbury Park Rd
    Watertown, CT  06795
      Tel: (203) 274-2523
      Fax: (203) 945-4225

     Addr: Telecommunications Industries Association (TIA)
    2500 Wilson Boulevard, Suite 300,
    Arlington, VA 22201
      Tel: (703) 907-7700        
      Fax: (703) 907-7727

    Underwriters Labs (UL) documents:
     Addr: Underwriters Labs Inc
    333 Pfingsten Road,
    Northbrook, Illinois 60062-2096 USA
     Tel:  (800) 676-9473 (from CDN/USA East coast)
    (800) 786-9473 (from CDN/USA West coast)
    (708) 272-8800 (International)
     Fax:  (708) 272-8129
     MCI Mail: 254-3343

--------------------------END OF CABLING FAQ---------------------------

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